If musicians were measured not by the number of records they sold but by the number of peers they influenced, JJ Cale would have been a towering figure in 1970s rock ‘n’ roll.

His best songs like “After Midnight,” “Cocaine” and “Call Me the Breeze” were towering hits — for other artists. Eric Clapton took “After Midnight” and “Cocaine” and turned them into the kind of hard-party anthems that defined rock for a long period of time. And Lynyrd Skynyrd took the easy-shuffling “Breeze” and supercharged it with a three-guitar attack that made it a hit.

Cale, the singer-songwriter and producer known as the main architect of the Tulsa Sound, passed away Friday night at Scripps Hospital in La Jolla, Calif. His manager, Mike Kappus, said Cale died of a heart attack. He was 74.

While his best known songs remain in heavy rotation on the radio nearly 40 years later, most folks wouldn’t be able to name Cale as their author. That was a role he had no problem with.

“No, it doesn’t bother me,” Cale said with a laugh in an interview posted on his website. “What’s really nice is when you get a check in the mail.”

And the checks rolled in for decades. The list of artists who covered his music or cite him as a direct influence reads like a who’s who of the Rock and Roll Hall of Fame — Clapton, Neil Young, Tom Petty, Johnny Cash, Mark Knopfler, The Allman Brothers, Carlos Santana, Captain Beefheart and Bryan Ferry among many others.

Young said in Jimmy McDonough’s biography “Shakey” that Cale and Jimi Hendrix were the best guitar players he had ever heard. And in his recent memoir “Waging Heavy Peace,” Young said Cale’s “Crazy Mama” — his biggest hit, rising to No. 22 on the Billboard singles chart — was one of the five songs that most influenced him as a songwriter: “The song is true, simple, and direct, and the delivery is very natural. JJ’s guitar playing is a huge influence on me. His touch is unspeakable.”

It was Clapton who forged the closest relationship with Cale. They were in sync musically and personally. Clapton also recorded Cale songs “Travelin’ Light” and “I’ll Make Love To You Anytime” and included the Cale composition “Angel” on his most recent album, “Old Sock.” Other songs like “Layla” didn’t involve Cale, but clearly owe him a debt. The two also collaborated together on “The Road to Escondido,” which won the Grammy Award for best contemporary blues album in 2008.

Clapton once told Vanity Fair that Cale was the living person he most admired, and Cale weighed the impact Clapton had on his life in a 2006 interview with The Associated Press: “I’d probably be selling shoes today if it wasn’t for Eric.”

That quote was typical of the always humble Cale. But while Clapton was already a star when he began mining Cale’s catalog, there’s no doubt the music they shared cemented his “Clapton is God” status and defined the second half of his career.

“As hard as I’ve tried I’ve never really succeeded in getting a record to sound like him and that’s what I want,” Clapton said in a “Fast Focus” video interview to promote “Escondido.” “Before I go under the ground, I want to make a JJ Cale album with him at the helm.”

Clapton described Cale’s music as “a strange hybrid. It’s not really blues, it’s not really folk or country or rock ‘n’ roll. It’s somewhere in the middle.”

Cale arrived at that intersection by birth. Born John Weldon Cale in Oklahoma City, he was raised in Tulsa. Buffeted by country and western on one side and the blues on the other, Oklahoma offered a melting pot of styles. Cale leaned on those styles as he spent his formative years in Los Angeles and Nashville, but he also used drum machines and often acted as his own producer, engineer and session player. He’d bury his own whispery vocals in the mix, causing the listener to lean in and focus.

“I think it goes back to me being a recording mixer and engineer,” Cale said in a 2009 biography on his website. “Because of all the technology now you can make music yourself and a lot of people are doing that now. I started out doing that a long time ago and I found when I did that I came up with a unique sound.”